Cardiovascular diseases (CVD) are a group of disorders of the heart and blood vessels including atherosclerosis and hyperlipidemia. CVD is the leading cause of death and morbidity in the European Union, and the prevalence of CVD among Irish population is on the increase. The progressive increase in the incidence of CVD is a major growing concern among many regulators and professionals involved in maintaining and promoting public health. CVD prevention remains unsatisfactory across Europe, largely due to poor control of CVD risk factors and the growing incidence of obesity.
Globally, a third of ischemic heart disease (IHD) is attributable to high cholesterol, and overall, raised cholesterol is estimated to cause 2.6 million deaths (4.5% of total) and 29.7 million disability adjusted life years (DALYS), or 2.0% of total DALYS. A 10% reduction in serum cholesterol in men aged 40 has been reported to result in a 50% reduction in heart disease within 5 years; the same serum cholesterol reduction for men aged 70 years can result in an average 20% reduction in heart disease occurrence in the next 5 years. In 2008, the global prevalence of raised total cholesterol among adults (≧5.0 mmol/l) was 39% (37% for males and 40% for females). Globally, mean total cholesterol changed little between 1980 and 2008, falling by less than 0.1 mmol/L per decade in men and women. The prevalence of elevated total cholesterol was highest in the WHO Region of Europe (54% for both sexes), followed by the WHO Region of the Americas (48% for both sexes). The WHO African Region and the WHO South East Asian Region showed the lowest percentages (22.6% for AFR and 29.0% for SEAR).
Lactic acid bacteria (LAB) are a genetically diverse group of bacteria that by definition, ferment sugars predominantly to lactic acid. LAB strains are naturally present in environments rich in organic matter, such as food and dairy products and in the mammalian digestive tract. LAB strains are also widely added as starter cultures in the dairy industry and have a long history of safe use, with most being generally recognised as safe (GRAS) or having the Quality Presumption of Safety (QPS) status, according to Federal Department of Agriculture (FDA) and European Food Safety Authority (EFSA), respectively. Some commercial LAB strains and many other microorganisms have been reported to produce exopolysaccharides (EPS). The biological function of EPS is known to be diverse, and includes a contribution to cell protection and survival, protection against environmental stresses, cell adherence, and it plays a role in pathogenesis and symbiosis. EPS can also be advantageous during dairy and non-dairy food fermentation and are used in the food industry as biothickening ingredients. The presence of EPS improves texture, decreases the risk of syneresis and improves techno-functional properties of dairy products. Some EPS-producing LAB strains are reported to spoil beverages, such as wine and cider with an undesired ropiness, down-grading the quality of the products.
In recent years, health benefits have been described for bacterial EPS. For example, EPS produced by commensal gut microorganisms have been demonstrated to play a role in the immune system through communication with the mammalian host. EPS was shown to modulate the gut microbial population, while other EPS-producing LAB strains were demonstrated to exert potential health benefits such as anti-tumoral, antiulcer, and immunostimulatory properties. Furthermore, dietary EPS have been reported to reduce blood pressure and exhibit cholesterol-lowering activities, and ingestion of EPS have been reported to exhibit immunogenic effects, gastrointestinal health and anti-carcinogenic effects.
Cholesterol-lowering properties of EPS and EPS-producing microorganisms have been studied in vivo and in vitro. EPS isolated from Lactococcus lactis subsp. cremoris SBT 0495 was reported to enhance the metabolism of serum cholesterol in rats. Animals fed kefiran, an EPS produced by Lb. kefiranofaciens, reduced total cholesterol in serum and reduced low-density lipoprotein (LDL)-cholesterol concentrations in the liver of animals fed kefiran. Another study demonstrated a reduction in total cholesterol in the liver of cholesterol-fed hamsters when fed milk kefir. Intake of kefiran, the EPS produced by microorganisms present in kefir grains, also greatly reduced the size of atherosclerotic lesions in cholesterol-fed rabbits. It has been suggested that EPS produced by LAB interact with cholesterol in a manner like dietary fibre.
Currently, there is a lack of information and understanding showing the cholesterol-lowering abilities of in situ produced EPS. It is therefore an object of the present invention to overcome at least one of the above-mentioned problems.